Lens Leucine Aminopeptidase (LAP) has been associated with cataractogenesis. We have two categories of projects in progress. 1. Localization of leucine Aminopeptidase in lens thin sections. This work will tell if LAP is associated with a specific age-related process, since different developmental zones of the lens can be identified. By repeating these tests in diseased lenses, we will investigate the relationship of LAP to cataractogenesis. 2. Molecular studies: Photoaffinity labels are being used to identify the amino acid residues at the active site. An NMR study of the distance between substrate and activation site metal is in progress. X-ray diffraction patterns are being collected in an attempt to define the three-dimensional structure of the molecule and the placement of the amino acid residues and metal atoms within that structure.